Nontopological spatially localized time periodic excitations coined discrete breathers are generic solutions for lattice Hamiltonians. I present recent results including the spatial decay of discrete breathers in systems with interactions decaying algebraically in space, the properties of the static deformation accompanying a breather excitation in low-symmetry lattice Hamiltonians with Goldsto...

We show that the process of spontaneous symmetry breaking can trap a field theoretic system in a highly non-trivial state containing a lattice of domain walls. In one large compact space dimension, a lattice is inevitably formed. In two dimensions, the probability of lattice formation depends on the ratio of sizes Lx, Ly of the spatial dimensions. We find that a lattice can form even if R ≡ Ly/...

We study the heavy charge potential in the Coulomb phase of pure gauge compact U(1) theory on the lattice. We calculate the static potential VW (T, ~ R) from Wilson loops on a 16 × 32 lattice and compare with the predictions of lattice perturbation theory. We investigate finite size effects and, in particular, the importance of non–Coulomb contributions to the potential. We also comment on the ...

This paper presents a novel photonic bandgap (PBG) structure for microwave integrated circuits. This new PBG structure is a two-dimensional square lattice with each element consisting of a metal pad and four connecting branches. Experimental results of a microstrip on a substrate with the PBG ground plane displays a broad stopband, as predicted by finite-difference time-domain simulations. Due ...